Two New Species of Miniature Tetras of the Genus Priocharax (Teleostei: Characiformes: Acestrorhamphidae) from the Rio Purus and Solimões Drainages, Amazonas, Brazil

Two new miniature tetra species of the genus Priocharax Weitzman and Vari 1987 are described, raising the known species diversity to twelve. Priocharax is characterized by several paedomorphic features such as reductions in the laterosensory system, number of fin rays, ossification of parts of the skull and the presence of a larval rayless pectoral fin in adults. The species described are found in the Rio Purus and Solimões drainages, in the state of Amazonas, Brazil and are diagnosed among themselves and from other species of the genus by the combination of meristic and osteological characters. Furthermore, the two species differ in overall body shape, with one having a deeper body and the other a more streamlined form. Sexual dimorphism was observed in both species. Molecular species delimitation analyses support the distinctiveness of these species. Similarly to Priocharax britzi and to P. conwayi, the specimens analyzed here were collected within and around protected areas, highlighting the importance of these areas for conservation and biodiversity knowledge.